Radar level gauging (RLG) to measure the level of a filling material, such as a liquid or a solid like a granulate is an increasingly important method for level gauging in tanks, containers, etc. Many different types of RLG systems are previously known. An example of such a systems is disclosed in U.S. Pat. No. 7,106,247 assigned to Rosemount Tank Radar, and includes an antenna inside the tank and an electronics unit containing transceiver circuitry and processing circuitry outside the tank. There are many ways to connect the electronics unit with the antenna in the tank, typically including some sort of wave guiding structure or a coaxial connector,
However, in some applications it is useful to arrange the electronics unit of the RLG so as to be easily replaceable and exchangeable. Also, in some applications, it is desirable to connect several electronics units providing functionally independent measuring channels to the same antenna. Independent radar level gauges using the same physical antenna but otherwise electrically independent provides redundancy at a low cost. For example, to connect more than one sensor to one antenna is a very cost effective way to implement a system with a level sensor and an independent overfill alarm, etc, and has gained wide acceptance among users and authorities.
An example of such a system using several channels for feeding one and the same antenna is disclosed in WO 03/025523, assigned to Rosemount Tank Radar. FIG. 1 shows an example of a prior art arrangement of this kind, with three electronics units 101, 102, 103 connected to a waveguide 104 connected to an antenna (not shown). The electronics units are connected to the waveguide by means of a connection device, for example a turnstile junction 105. The electronics units are connected to the connection device using conventional terminals, such as coaxial connectors. One of the electronics units is connected to a first probe 106 coupling energy having a first polarization into the waveguide. The other two electronics units are connected to a second probe 107 via a power divider 108 which is part of the turnstile junction.
Another example is disclosed in U.S. Pat. No. 7,701,385, assigned to Rosemount Tank Radar. In this case, two or more electronics units are combined to form a pineapple slice shape, the hole of which may form part of the wave guide,